In the field of production of tights, pantyhose and similar knitted articles, there is a continuous search for new methods and systems for automating the knitting process, to obtain a seamless continuous article or garment, knitted on a circular machine in a single production process.
Some searches are based on a process developed in the '60s, which provides for a tubular article to be knitted during a single process onto a circular knitting machine starting from an end of a first leg piece up to an end of a second leg piece, knitting three subsequent tubular portions or sections to form, in addition to the two leg pieces, the body of the article. The tubular article unloaded form the circular knitting machine is then cut in the central area to form an opening around which an elastic edge is sewn to form the body waist. This known process is detailed in the GB-1235361. To increase its fit, the body is knitted with wider stitches, so that the central portion of the tubular article or garment has a slightly greater section than the section of the leg pieces.
The method described in GB-1235361 is very fast as it can be performed on a circular knitting machine with continuous motion. However, the article produced by means of this method had low success as the body, being formed with a tubular fabric with the same number of stitches per raw as the tubular legs, did not fit sufficiently closely. More in particular, the body height was too limited and the elastic edge was too close to the crotch line.
Many improvements to this method have been studied, trying to overcome the limits and drawbacks thereof.
U.S. Pat. No. 2,962,884 discloses a method wherein, after having knitted the first leg piece and before knitting the second leg piece, two pockets of fabric are produced on the circular knitting machine by knitting with reciprocating motion rows of gradually decreasing and then increasingly length. The two pockets knitted with reciprocating motion form the body of the garment, which thus fits more than the body produced with the method originally described in GB-1235361.
However, the method disclosed in U.S. Pat. No. 2,962,884 is particularly slow as most of the garment, and especially the whole body, is knitted by means of reciprocating motion with only one feed, i.e. feeding only one yarn to the needle cylinder and therefore forming only one row of stitches at every rotation of the needle cylinder. Regardless of this inconvenience, at the present time seamless tights are produced using this method. Especially, the seamless tights of the Austrian company Wolford are produced with this method, combining continuous motion for knitting the leg pieces and reciprocating motion for knitting the body.
U.S. Pat. No. 4,022,035 describes a method for producing tights in a single process on a circular knitting machine with a technique similar to that of U.S. Pat. No. 2,962,884. In this further embodiment, while knitting the body central portion with reciprocating motion the needles are precisely selected so as to form the opening of the garment directly onto the circular machine. Also this process is particularly slow, as it is mostly made with reciprocating motion of the needle cylinder.
There is therefore a need to further improve the methods for knitting pantyhose, tights and similar articles or garments having a body and two leg pieces, using a single process onto a circular knitting machine, which overcome or reduce the drawbacks of the known methods that are still used.